A dielectric material, such as Teflon , is placed between the plates of a parallel-plate capacitor without altering the structure of the capacitor. The charge on the capacitor is held fixed. How is the voltage across the plates of the capacitor affected? 1. The voltage decreases because of the insertion of the Teflon . 2. The voltage becomes infinite because of the insertion of the Teflon . 3. The voltage increases because of the insertion of the Teflon . 4. The voltage becomes zero after the insertion of the Teflon . 5. The voltage is not altered, because the structure remains unchanged.